Crystal contact device



Nov 24, 1953 E. s. JAMES ETAL CRYSTAL CONTACT DEVICE Filed May 10, 1950 FIGS FIG.4

INVENTORS EMRYS GWYNNE JAMES 2 way 0504/? EDGAR UNDEI-L ATTORNEY lPatented Nov. 24, 1953 UNITED STATES PATENT OFFICE CRYSTAL CONTACT DEVICE and Aubrey Oscar Edgar gland, assignors to Hazel- Emrys Gwynne James Lindell, Wembley, En

tine Research, Inc., of Illinois Chicago, 11]., a corporation'- Applicatlon May 10, 1950, Serial No. 161,126

General The present invention is directed toimprovements in electrical crystal contact devices. More particularly, the invention relates to electrical crystal contact devices of the kind comment, such as the contact adapted to provide an external metallic connection to the element, but only refers to contact members of the kind which are in substantially point contact with the element, commonly known as whiskers." v

Crystal contact devices, which include two contact members having two contact points in spaced engagement with the surface of the crystalline element, are known in the art and these devices may be used for amplification of electrical signals. For certain applications of these devices, such as in transistor-type signal repeaters, the spacing of the points of contact substantially afiects the repeater characteristics. Hence this spacing must be accurately determined. Heretofore it has been relatively difficult to construct such devices in a manner which readily lends itself to the use of mass-production techniques and yet which provides an accurate predetermined spacing of the points of contact.

It is another object of the invention to provide an electrical crystal contact device which has an accurate spacing between the contact points engaging the semiconducting crystal of the device and yet which is relatively inexpensive to manufacture.

In accordance with the present invention, an electrical crystal contact device comprises a body of insulating material, two substantially parallel wires having a predetermined spacing therebetween secured in insulated relation to the body and having the ends thereof extending beyond the body. The crystal contact device also includes a semiconducting crystal having a contact surface and a conductive support maintaining the body and the crystal in fixed relation thereon with the contact surface disposed at an acute angle with reference to the axis of the wires and 2 Claims. (Cl. 317-235) making substantially a point contact with two corresponding ends of wires.

Preferably the winding is performed by machine. The crystalline element may be supported by a resilient strip attached to the body. The body may be molded around the wires while they are maintained at the required spacing by the form. The wires may be left with planar ends, the element being positioned so that the contact points lie on the periphery of the planar ends.

For a better understanding of the present invention, together with other and further objects thereof, reference is had to the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims.

One method of manufacturing a crystal contact device according to the present invention will now be described by way of example with reference to the accompanying drawing wherein Fig. 1 is a perspective view representing one stage in the production of the device; Fig. 2 is a perspective view of the completed contact-carrying portion of the device; Fig. 3 illustrates in perspective an alternative form for the contactcarrying device; and Fig. 4 is a sectional elevation view of a complete crystal contact device utilizing the alternative form of construction illustrated in Fig. 3.

Description of Fig. 1 and Fig. 2 operations Referring now to Fig. 1, a few turns of fine wire 3 of, for example, tungsten or Phosphor bronze, are wound around a form I comprised by a framework in the form of a hollow open ended rectangular box. These turns are wound around two opposite sides and across the openportion of the turns lying across one end. These portions of two of the turns are firmly secured to the block by a suitable insulating cement 4, such as a synthetic resin plastic cement. All the turns are then severed at points nearjopposite edges of the form I and the block 2"is withdrawn from the form framework so that the block is left with two straight wires secured to one surface, the wires having their longitudi- Description of Fig. 3 structure In the modification of the above arrangement illustrated in Fig. 3, the wires 3 may be fixed within a block or cylinder of insulating material, for example by molding the block or cylinder around the appropriate portions of the turns wound on the framework (not shown), or byv securing the wires 3 to the surface of one block 2 as described above and then securing another block to the first block, thereby sandwiching the wires 3 between the two blocks to form a I unitary structure. Fixing the wires within a block or cylinder in the manner just mentioned.

overcomes the likelihood of the wires being forced off the block by lateral pressure when the wires are brought into engagement with a.

crystalline element in'the manner presently to be described.

Description of completed contact device of Fig. 4

Fig. 4 is a sectional elevation view of a completed crystal contact device incorporating the form of construction illustrated in Fig. 3. The two wire contacts 3 are firmly held between the two blocks of insulating material 2 and 5 and the complete unit is mounted onto a shaped support 8 preferably of metal. This support has a bent portion 9 to which is firmly fixed a crystal 6 and a lead 1 which has an area of contact with a portion of the crystal. The bent portion 9 is preferably disposed at an acute angle with reference to the lower surface of the main por-v tion of the support 8. In assembly, the lower block 2 of the contact holder can be adjusted upon the support 8 until it is in such a position that satisfactory point contacts are obtained by the wires 3 against the surface of the crystal 6, the lower surface of the contact holder being then permanently affixed to the support 8 by a suitable cement, such as synthetic resin plastic cement. The whole device may, after adjustment, be fitted within a protective container of some material, such as glass, leads being provided from the ends of the contact wires remote from the crystal.

The contact ends of the wires 3, 3 may be pointed in known manner, for example by etch-= ing, or they may be left with planar ends perpendicular to the longitudinal axes of the wires.' In this latter case, in order to provide substantially point contacts, the contact surface of the element will be positioned to lie in a plane which is inclined at an angle to the planar ends of the wires less than ninety degrees. The contact points for the wires will then be points on the' periphery of the planar ends. In any arrangement, however, the axes of the wires are prefer-' ably not perpendicular to the plane in which the contact surface of the crystalline element lies.

The reason for this is that if, when bringing the ends of the wires into contact with the element, one wire makes contact with the element first, this wire can slide over the surface until the other wire comes into contact with the element.

As it may be desired to employ contact members using wire of 0.05 to 0.15 millimeter diameter with a spacing of the order of 0.1 to 0.2 millimeter between the longitudinal axes of the wires, it will be appreciated that the present invention provides a relatively simple method of spacing the wires at a predetermined distance apart.

While there have been described what are at present consideredto be the preferred embodiments of this invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the invention, and it is, therefore, aimed to cover all such changes and modifications as fall within the true spirit and scope of the invention.

What is claimed is:

1. An electrical crystal contact device comprising: a body of insulating material; two substantially parallel wires having a predetermined spacing therebetween secured in' insulated relation to said body and having the ends thereof extending beyondsaid body; a semiconducting crystal having a contact surface; and a conductive support maintaining said body and said crystal in fixed relation thereon with said contact surface disposed at an acute angle with reference to the axes of said wires and making a substantially point contact with two corresponding ends of said wires.

2. An electrical crystal contact device comprising: a laminated body of insulating material including two portions secured together at contiguous surfaces thereof; two substantially parallel wires having a predetermined spacing therebetween secured in insulated relation between said portions and having the ends thereof extending beyond said body; a semiconducting crystal having a contact surface; and a conductive support maintaining said body and said crystal in fixed relation thereon with said contact surface disposed at an acute angle with reference to the axis of said wires and making a substantially point contact with two corresponding ends of said wires.

EMRYS GWYNNE JAMES.

AUBREY OSCAR EDGAR LINDELL.

References Cited in the file of this patent UNITED STATES PATENTS 

